Compensator for nail driving mechanisms



Aug. 3, 1937.

H. E. TWOMLEY COMPENSATOR FOR NAIL DRIVING MECHANISMS Filed Oct. 27,1934 2 Sheets-Sheet 1 V 1 i I I! 4a: mmimi'winnnn nnum! 3 7 i 3 v i 2Sheets-Sheet 2 H: E. TWOMLEY COMPENSATOR FOR NAIL DRIVING MECHANISMS-Filed oct'. 27, 1954 Aug. 3, 1937.

Patented Aug. 3, 1937 iJl'lED STTiEl TET COMPENSATOR FOR NAIL DRIVINGMECHANISMS Application October 27, 1934, Serial No. 750,289

Claims.

My invention relates to nailing machines, and has particular referenceto a device for automatically adjusting the length of movement ofnaildriving mechanisms, or automatically compeneating forvaryingdistances through which the nails are to be driven.

In nailing machines for nailing box parts together it frequently occursthat some of the box parts vary considerably in size and thickness sothat a machine which is set to nail a given size of box with given sizesof parts will not drive nails accurately if there is a slight variationin the thickness of the parts to be nailed together. This isparticularly apparent in the manufacture of boxes where the nailingmachines are em"- ployed to nail side, bottom and top boards upon cutends wherein the thickness of the shook or side, bottom and top boardsvaries considerably, so that a machine which is correctly adjusted todrive nails flush with the surface of the shocks, or side boards, will,when a shook of different thickness is encountered, drive the nailseither below the surface of the board or not quite flush with thesurface of the shook or board. This is undesirable primarily because itplaces an undue and unnecessary strain upon the operating parts of themachine, and, secondarily, because it does not produce a strong,substantial box as would be produced were the nails always driven to aposi- 30 ticn just flush with the top: surface of the board or shook.

In the making of certain types of boxes, such as those employed for thepacking and transportation of fruits, it is the common practice to makecertain of the boxes whichare to be used for domestic shipment with theside, bottom and top boards of a predetermined thickness, while, if theboxes are to be used in export service, the sides, bottoms and tops ofthe boxes-are formed of either shocks or boards whichare of twice thedomestic thickness or the sides, bottoms and tops of the boxes areconstructed by applying two of the boards, one superimposed upon theother so that the nails which are to be driven into these export boxesmust be driven flush with a board equaling twice the thickness of thedomestic box.

It is, therefore, an object of my invention to provide a nailingmechanism which, when adjusted for any predetermined size of box, .orany predetermined thickness of shook or boards which are to be usedthereon, can also be used to drive the nails in boxes which varyslightly in dimensions or in which the boards or shocks employed varyconsiderably in thickness. 7

Another object of the invention is to provide a nailing mechanism of thecharacter set forth in the preceding paragraph wherein it is impossibleto'apply greater than a predetermined force to the nail, and it isimpossible to press or drive the nail to a position further than flushwith the top surface of the board or shook through which the nail is tobe driven.

Another object of the invention is to provide a nailing mechanism of thecharacter set forth, in which the nail-driving punches employed areconnected to a nail driving head which is permitted to travel the samedistance irrespective of the thickness of the box or shook which isbeing operated upon and in which the nail punch will only move throughadistance necessary to drive the nail flush with the top surface of theboard or shook.

Another object of the invention is toprovide a nail-driving mechanism ofthe character set forth, in which the nail punches are connected to thenail-driving head by mechanism which will apply only a predeterminedpressure to the nail.

Another object of the. invention is to provide a nail-driving mechanismin which the nail punches employed are connected to the nail-drivinghead and to nail chucks so that the nail punches can only be driven to apoint flush with the lower surface of. the nail chucks and in which thenail punches are positively stopped in such position irrespective of themovement of the naildriving head.

Anotherobject of the invention is to provide a nail-driving mechanism inwhich the nail punches are permanently connected to the naildriving headby link mechanism which provides for the transmission of a predeterminedforce from the driving head to the nail punch but in which, when suchforce is exceeded, will so change the direction'in which the force istransmitted between the driving head and the punch that theeffectiveforce transmitted to the nail punch will be reduced substantially tonothing.

Other objects and advantages will be apparent from a study of thefollowing specifications, read in connection with the accompanyingdrawings,

wherein V Figure 1 is a side elevational View shown partly in section ofa nail-driving mechanism constructed in accordance with my invention;

. Figure 2 is a front elevational view, partly in section. of themechanism illustrated in Figure 1;

Figure 3 is a sideelevational view partly in section illustrating theoperation of my naildriving mechanism when the box or shook is of apredetermined thickness corresponding to the initial setting of thenail-driving mechanism;

Figure 4 is a view similar to Figure 3, illustrating the operation oimynail-driving mech- 'anism when the shook is of slightly greaterthickness than that shown in Figure 3;

Figure 5 is a view similar to Figure 3, illustrating the operation of mynail-driving mechanism when the shook or board operated upon is ofconsiderably greater thickness than that shown in Figure 3.

Referring to the drawings, I have illustrated only a portion of thenail-driving machine, it

being understood that the nail-driving mechanism illustrated herein maybe readily adapted to any well-known type of nail-driving mechanism orbox-making mechanism, such as are shown in United States Letters PatentNo.

granted to George David Parker on March 9,

1926, for Combined cover press and nailing machine.

The nailing machine, or a portion of which is illustrated herein,comprises the usual frame,

not shown, from which rises uprights I constituting verticallyextending. guide rails upon which a nail-driving head 2' is reciprocablymounted. The rails I, on opposite sides of the machine, may be connectedby any suitable cross bars or braces,

illustrated herein as a pair of rods 3 and 4 which are connected to aclamp 5 mounted directly upon the upper'end of the rail I. The crosshead 2 isillustrated as comprising a bearing member 6 slidably mountedupon the upright or rail I, it being understood that upon the oppositeside of the machine a similar bearing 6 is mounted upon the rail at thatside of the machine. The bearings 6 on opposite sides of the machine areinterconnected by means of. cross bars or rods 1 and 8 which in turnconstitute hangers upon which the nail-driving mechanisms may besupported.

The nail-driving mechanisms may comprise a nail chuck assembly Ill,illustrated herein as comprising an elongated guide I I upon the lowerend of which is mounted a nail chuck body I2 having a pair of jaws I3normally held inclose relation with each other by means of a pair ofsprings I 4' and I 5 mounted upon opposite sides of the guide II. Thenail chuck jaws I3.may be constructed in any well-known manner, as thatillustrated herein as a pair of blocks, the'meeting faces of' which areprovided with suitable complementary grooves I6 adapted to receive andhold a nail I! in a vertical position aligned with the vertical axis ofthe guide I I.

As will be understood by those skilled in the art, the lower face of thechuck body I2 constitutes the nailing line or lower limit to which thenail II shouldbe driven, such nail chuck body I2 being usually broughtinto contact with the upper surface of the board tobe nailed so that thenail, when driven completely through the nail chucks, will be ju'stflushwith the upper surface of the board so nailed.

The nails are driven'by a nail driver I9 reciprocably mounted in theguide I I. The nail driver I9' is preferably formed as a rod having anupper portion of enlarged diameter reciprocabl'y mounted in an-enlargedvertical bore 20 in the guide II} while the'nail' engaging portion ofthe nail driver I9 is preferably formed with a reduced diameteroperating in a vertical bore I8 extendingbelow the bore 20 and, ofappropriately' lesser diameter.

The guide I I is also provided with a nail channel which may be of anysuitable construction to guide a nail into the nail chucks in theposition shown in Figures 1 and 2, the form of the nail channelillustrated herein comprising a block 22 having a bore 23 extendingtherethrough such that when the block 22 is assembled upon the guide I Iand held in place there-on by means of a spring 24 nails dropped intothe upper end of the bore 23 will slide downwardly through the guideinto the position shown in Figures 1 and 2.

The upper end 20 of the nail driver I9 is illustrated as being connectedto a cross head 25 by means of a suitable nut 26. The cross head 25 isillustrated as having a pair of pins 21 and 28 extending laterallytherethrough, one on each side of the nail driver I9 and spaced aconsiderable distance from the longitudinal axis of the nail driver I9.The pin 21 constitutes a bearing upon which is mounted a pair of links29 and 3!, while the pin 28'mounts a pair of similar links 3I and 3I-.The links 29 and 30 on the righthand side, as viewed in Figure 1, thelink 29 being illustrated in Fig. 1 as partially broken away so as topermit a view of the link 3I behind the same, are interconnected bymeans of a pin 32 which extends parallel to the pin. 21 but is offsetslightly from a vertical plane drawn through the pin 21, the pin 32being connected directly with the cross bar I by means of a secondarylink 33, one end of which is mounted upon the cross bar I to freelyrotate thereon, while the other end of the link 33 is free to rotateupon the pin 32.

Upon the opposite, or left-hand, side of the device, as' shown in Figure1, the links 33 and 3I' are similarly interconnected by means of a pin34 which extends parallel to the pin 28, but is offset slightly from thevertical plane of the pin 28. The pin 34 constitutes a bearing uponwhich the lower end of a secondary link 35 is rotatably mounted, theupper end of the link 35 being rotatably mounted upon the cross bar 8.

The links Hand 30 upon the front side of the nail-driving mechanism, asviewed in Figure 1, together with the secondary links 33 and 35,constitute two sets of toggle links connecting the cross head 25 withthe cross bars I and 8, while the corresponding links 3I and 3! upon therear side of the nail-driving mechanism, as viewed in Figure 1, togetherwith the links 33 and 35, constitute a similar pair of toggle linksinterconnecting the cross head 25 with the cross bars "I and 8.

With the construction thus far described, it will be apparent that whenthe nail-driving head 2 is drawn downwardly by connecting rods 36connected to the bearings 6 in the usual manner employed for operatingnail-driving heads of nailing machines, the cross bars I and 8 will bedrawn downwardly and will carry with them the nail drivers I9.

As will be understood by those skilled in the art of nail-drivingmachines, the usual practice for operating the nail-driving head 2 is toconnect the connecting rods 36 to rotatable crank pins so that upon eachrevolution of the crank pins the nail-driving head 2 will be drawn downthrough a predetermined distance and then returned to its originalposition, such as that illustrated in Figures 1 and 2. It follows,therefore, that the nail-driving head 2 will, upon each revolution ofthe crank'pins, be drawn downwardly through the same distance, and thatthe nail drivers I9 will be moved downwardly through the same distanceupon each operation of the nail-driving head 2. When the device is to beused to nail a shook 38 to a box end H the machine may be originallyadjusted so that when the chuck body I2 is brought into contact with theupper surface of the shook 38, the nail driven by a complete downwardmovement of the naildriving head 2 will be just flush with the uppersurface of the shook 38. Thus if the shook 38 is used and is of apredetermined thickness for which the machine is initially adjusted, thecomplete downward movement of the nail-driving head will just drive thenail flush with the upper surface of the shook. 1 By referring,particularly, to Figures 1, 2, and 3, it will be noted that the shoulder39, formed by the junction of the enlarged portion of the nail driver l9with its reduced portion, may be employed as a limit stop, limiting themovement of the nail driver 59 relative to the nail chuck assembly I0 byforming a similar shoulder 40 upon the interior of the guide ll againstwhich the shoulder 39 abuts when the nail punch has moved apredetermined distance through the nail chuck assembly. As illustratedherein, this limit of movement is just such as will bring the lower endof the nail driver exactly flush with the lower surface of the chuckbody l2 so that if the chuck body rests upon the uppersurface of theshock 3B the nail driver is will move to a position just flush with theupper surface of the shook 38. Thus the lower surface of the chuck bodyif! constitutes the nailing line to which level the nails will be drivenat all times. If the nail chuck body is stopped prior to reaching thelowermost level, as shown in Figure 4, it follows that the nail driverl9 will also be stopped at the new level at which the chuck body H. hascome to rest, because the shoulders 39 and have come 40 together.

As will be understood by those skilled in the art of nailingmachines,the nail chuck assembly it may be supported directly uponv thenail driver l9 so that it lifts and lowers slightly with 4.5 themovements of the nail driver l9, as by a set screw 5t extending throughthe guide ll into a keyway 5! formed in the enlarged upper portion 2!)of the nail driver l9, which will lift the nail chuck assembly Illslightly above the level of the box parts 31 and 38 when thenail-driving head is lifted to its normal position as shown in Figures 1and 2. The purpose of providing a slight vertical movement for the nailchuck assembly is to permit a greater amount of freedom for the operatorof the machine to place the box parts 3i and 38 in the machine prior tothe actual nailing operations; while, when the box parts are inposition, the nail chuck is permitted to move down slightly to engagethe upper sur- 0 face of the shock 38.

If, however, the box parts are not exactly of the dimensions illustratedin Figure 3, but are slightly larger as shown in Figure 4, in which theshook 33a is illustrated as being of slightly 35 greater thickness thanthe shook 38, it will be apparent that while the nail-driving head 2 ismoved downwardly to the same distance, the nail chuck assembly It andthe nail driver I 9 will not be capable of moving to the'same lowerposition 7 as shown in Figure 3, but will be stopped at a higher point,depending upon the thickness of the shock 38a.

By referring to Figure 4, it will be apparent that the nail driver l9has moved down through 75 the nail chuck assembly ID to position itsshoulder 39 directly upon the shoulder 4!! formed upon the guide l I,thus bring the extreme lower end of the nail driver I9 flush with thelower surface of the chuck body 112, but the chuck body i2 is nowresting upon the upper surface of the shook 38 at a higher level thanthat illustrated in Figure 3. Thus downward movement of the nail driverl9 has been arrested prior to the arrival of the nail-driving head 2" toits lowermost position.

From an inspection of Fig. 1, it will be observed that while the rod 8and the pin 34 are in substantial vertical alignment so that downwardmovement of the driving head 2 will transmit a direct vertical force tothe links 39, the pin 28 which connects the link 30 with the cross head25 on the nail punch is offset out of vertical alignmentwith the pin 35.Thus the downward movement of the driving head 2 will transmit a forceto the nail driver E9 of which the vertical component will besubstantially large. The same arrangement of offset of the pin 21relative to the vertical alignment of the pin 32 and the rod Bl isemployed for the opposite toggle links 29 and 33 and the two sets oflinks 3ll-35 and 23-33 may be interconnected by means of a relativelylight spring 43 tending to hold these links from outward movement. Thusthe force exerted by the nail-driving head 2 upon the nail driver I9during the movement of the driver l9 down through the guide H, will besubstantially the same as though there was a direct connection of thenail driver l9 with the cross head 2 until the shoulders 39 and 4!] comein contact with each other. cient to drive the nail through the chuckassembly and into the board or chuck. However, when the shoulders 39 and40 engage each other, further downward movement of the nail-driving head2 will cause the toggle links 3ll35 and 2933 to break, thus relievingfurther pressure upon the nail driver l9.

It will be apparent from an inspection of Figure 1 that the spring 43 isconnected to the links 29 and 30 upon outwardly extending arms 452%which extend to a considerable distance laterally of the pins 32 and 34,respectively. Thus a slight breaking of the toggles 30-35 and 2933 willswing the outer ends of the arms 43 toward horizontal alignment with thepins 27 and 28, the efiect of which is to reduce the vertical componentof the force transmitted by the toggle links from the nail-driving head2 to the nail driver 119 to greatly reduced value, approaching zero, asthe ends of the arms 43' approach horizontal alignment with the pins 2'!and 28. The effect of the outward movement or breaking of the togglelinks 3ll35 and 29-33 will, therefore, be tosubstantially cancel anydownward pressure upon the nail driver l9 after the shoulders 35 and 40have been brought into engagement with each other. The toggle links 3!and This force, therefore, will be suifi-.

3! at the rear, as viewed in Figure 1, are similarly interconnected by aspring 42 connecting two arms identical with the arms 43' and operatingin the same manner so that by properly selecting the strength of thesprings 42 and 43, and by properly selecting the length of the extendingarms 43', the desired force to be exerted upon the nail by the initialmovement of the driving head 42 may be adjusted. Also, it will beobserved that the links 29 and 39 have inwardly extending arms 4'!formed thereon, the meeting surfaces of which constitute stops limitingthe inward movement or straightening 0f the toggle links 3035 and 29-43,and by properly selecting the lengths of the arms 4! the initialvertical component of the force transmitted from the nail-driving headto the nail punch 20 may be adjusted.

For convenience, the springs 42 and 43 may have one of their endsconnected to a single cross pin 44 which connects the arms 33 of thelinks 29 and 3!, while a similar pin 45 may be employed to interconnectthe links 36 and 3! to which the opposite ends of the springs 42 and 43may be secured, the springs being secured to the pins 44 and 45,preferably through a clevis 46 which will permit rotary movement of thepins relative to the springs without producing a bending torsion in thesprings. It will be apparent, therefore, that independent of thethickness of the shooks 38 and nail drivers they may be positioned belowthe upper surface of 'the particular shook through which the nail is to.be driven and no execessive force will be exerted either upon the naildriver or the shock assembly tending to crush the shock or tending todrive the nail l'l below the surface of the shocks 38 or 38a. Thus thetoggle joints provided by the links Z933, 3I33 and 39-35 and 3|'-35constitute a connecting device between the nail driver l9 and thenail-driving head 2 which will transmit a force necessary to drive thenail flush with the shock and then diminish the force, and then, eventhough further movement of the nail-driving head may occur,,the forceexerted by such further movement upon the nail driver will be sodiminished as to cause substantially no further pressure to be exertedupon the'nail punch. Thus while ample force may be transmitted toperform the nail-driving operations, no force is trans mitted tending toover-drive the nail.

7 By referring particularly to Figure 5, it will be apparent that eventhough the shook 381) shown therein is of considerably greater thicknessthan the shook 38a shown in Figure 4, the same results of driving thenail flush with the upper surface of the particular shook underconsideration will occur, the toggle connections moving outwardly to agreater or less distance depending upon the thickness of the shocks 38,38a or 38b through which the nail is to be driven.

WhileI have shown and described the preferred embodiment of my inventionherein, I do not wish to be limited to any of the details ofconstruction shown herein, except as defined in the appended claims. 7

I claim:

1. 'In a mechanism for driving nails through boards, a nail-driving headmovable through a predetermined distance toward said board, a naildriver, means connecting said nail driver with said nail-driving headfor movement therewith, said connecting means including means forlimiting the force exerted by said nail-driving head upon said naildriver to a predetermined value.

2. In a nail-driving mechanism, a nail-driving head movable through apredetermined distance upon each operation thereof, a nail driver, meansconnecting said nail driver with said nail-driving head to transmit theforce of the movement of said nail-driving head directly to said naildriver, yielding means on said connecting means operatively responsiveto the exertion of a predetermined resistance to movement of said naildriver for diminishing the force transmitted from said nail-driving headto said nail driver.

3. In a nail-driving mechanism, a nail-driving head movable through apredetermined distance upon each of its operations, a nail driver, linkmeans connecting said nail-driving head and said nail driver, movablethrough one position, transmitting the force of movement of saidnail-driving head in a direct line to said nail driver to anotherposition transmitting said force to said nail driver indirectly, andmeans on said link means operably responsive to the exertion of apredetermined resistance to the movement of said nail driver foryieldingly holding said link means in said first position until saidpredetermined resistance is exerted.

4. In a nail-driving mechanism, a nail-driving head movable through apredetermined distance upon each of its operations, a nail driver, atoggle link connecting said nail driver with said naildriving head andoperably responsive to the resistance opposing said nail driver formoving said toggle link from a position transmitting force from saidnail-driving head directly to said nail driver to a second positiontransmitting said force indirectly to said nail driver.

5. In a nail-driving mechanism, a nail-driving head movable through apredetermined distance upon each of its operations, a nail-driver,toggle link means connecting said nail-driver with said nail-drivinghead, the midpoint of said toggle link means being disaligned with theends of said toggle link means whereby resistance to movement of saidnail-driver will cause said toggle link means to yield, and meansopposing the yielding movement of said toggle link means.

HERBERT E. TWOMLEY.

